The protocol of Montreal for the protection of the ozone layer led to the end of the use of chlorofluorocarbons (CFCs). Less aggressive compounds for the ozone layer, such as the hydrofluorocarbons (HFCs) e.g. HFC-134a replaced chlorofluorocarbons. These latter compounds were indeed shown to provide greenhouse gases. There exists a need for the development of technologies which present a low ODP (ozone depletion potential) and a low GWP (global warming potential). Although the hydrofluorocarbons (HFCs), which are compounds which do not affect the ozone layer, were identified as interesting candidates, they exhibit a relatively high GWP value. There still exists the need to find compounds which exhibit a low GWP value. Hydrofluoroolefins (HFO) were identified as being possible alternatives with very low ODP and GWP values.
Several processes of production HFOs compounds, in particular of propenes, were developed.
WO2009/018561 describes the fluorination of 1230xa in continuous liquid phase in the presence of a catalyst in particular SbCl5. The desired product is the 244bb, that is the saturated product, the product 1233xf representing only a low fraction. The conditions of selected reactions are such that the medium of reaction is either only the catalyst or a catalyseur/1230xa mixture. US2009/0099396 describes the fluorination of 1230xa in 245eb in liquid phase, in a medium made up of catalyst, again SbCl5.
WO2007/079431 describes fluorination in liquid phase starting from the 1233xf, to prepare 244bb, which is a saturated compound.
WO2008/149011 describes fluorination in liquid phase in the presence of an ionic liquid of a propene. It is indicated generally that 1233xf and/or 1234yf (2,3,3,3-tetrafluoropropene) can be obtained by conversion of 1230xa.
WO2009/003084 describes fluorination in liquid phase in the absence of catalyst of 1230xa in 1233xf.
In the above patents, it is in general the gaseous phase which is analyzed. There is no evaluation of the rate of retention of the reactants in liquid phase whereas the organic liquid phase constitutes a large part of the material balance. However, phenomena of polymerization were observed in the liquid phase generating an important loss of output.
One thus seeks to limit the polymerization of the starting products, while preserving a high output of reaction. The limitation of the polymer formation will allow a continuous operation, without the risk of clogging the reaction zones and the feed ducts or the withdrawal pipes of reactants or products.